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Posted

Ok, say it is the middle of the day and you are accellerating beside another car down the road... why is it that you see there wheels start spinning backwards as they accellerate? Is the sun flickering or do you see in frames... or is it something else?

 

I have always wandered this since I was a little kid...

 

Thank you in advance!

Posted

Me too. We'd be driving down the highway at 60 or 70 mph. I'd look out the window... wandering... exploring... day dreaming... only to find the car beside us to have wheels spinning in the wrong direction.

 

WTF? I'm with my parents, so I know I'm not high...

 

 

It's called the "wagon-wheel effect," and this article explains it far better than I could:

 

http://en.wikipedia.org/wiki/Wagon-wheel_effect

 

 

This is your brain in a frying pan... :rolleyes:

Posted

It is said that your eyes view 24 "frames" each second. The reason that you're getting the impression that the wheels are going backwards is because every time your eye "captures a frame", one of the spokes of the wheel have been placed slightly behind the position of the spoke that was previously "further ahead" (the spoke you saw before is now probably half way down the wheel). This gives you the impression that the spoke has moved backwards. It's really hard to explain!

 

Whoops, just as I typed this I realized a link has been posted with the proper explanation. Oh well...

Posted
It is said that your eyes view 24 "frames" each second.

I think you are confusing research on the persistence of vision and the current rate at which theatrical films are shown (movies are played back at 24 frames per second, the eye and brain do not necessarily perceive at this specific rate, nor is that the limit of perception).

 

Although retinal neurons can respond to flicker rates as high as 120Hz (120 flickers per second), the flicker fusion threshold across individuals varies quite a bit.

 

 

The eye is not a camera. It is a complex interplay of receptors, biological machinary, and aggregate firing patterns which are sent to various parts of the brain for processing.

Posted
I think you are confusing research on the persistence of vision and the current rate at which theatrical films are shown (movies are played back at 24 frames per second, the eye and brain do not necessarily perceive at this specific rate, nor is that the limit of perception).

 

Although retinal neurons can respond to flicker rates as high as 120Hz (120 flickers per second), the flicker fusion threshold across individuals varies quite a bit.

 

 

The eye is not a camera. It is a complex interplay of receptors, biological machinary, and aggregate firing patterns which are sent to various parts of the brain for processing.

 

Lol, I think I was confusing myself with the persistence of vision. Thanks for pointing that out, and sorry for explaining wrongly...

Posted
sorry for explaining wrongly...

 

If you learned something from the exchange, then there is no need to apologize. ;)

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